Tetra alkyl lead



Patented June 11, 1935 UNITED STATES PATENT OFFICE TETRA ALKYL LEAD NoDrawing. Application March 9, 1932, Serial No. 597,800

19 Claims. (Cl. 202-57) This invention relates to the manufacture oftetra alkyl lead compounds and more particularly to the recovery of suchcompounds from a mixture of reaction products.

The process in most general use, at the present time, for themanufacture of tetra alkyl lead compounds comprises reacting an alkylhalide with a lead sodium alloy, cooling the resulting lead sludge, thendrowning it in water and then distilling with steam to remove the tetraalkyl lead compound. During this distillation, the particles of lead inthe sludge tend to cohere and form balls and sheets which rendereffective agitation impractical or impossible and which cannot beflushed from the still butrequire manual removal. Furthermore, the leadsludge remaining in the still retains substantial proportions of thetetra alkyl lead which it has, heretofore, been considered to beimpossible to recover by means of continued distillation.

In order to prevent this agglomeration of the metallic lead and thusovercome the many problems presented thereby, it has been proposed toadd to the lead sludge, before distillation; compounds which have adispersing action on the metallic lead and prevent the agglomerationthereof. Some of these compounds are glue, agar-agar, gums, engine oil,lard oil, toluene, and the like; and also certain inorganic salts suchas sodium sulfide, sodium carbonate, sodium sulfate, and thecorresponding potassium salts.

While these compounds greatly improve the condition of the sludge andrender it more fit for proper working in the still, they have notbeenproved to be entirely satisfactory as they do not entirely preventagglomeration of the lead. Furthermore, even with the use of thesecompounds, it has been impossible to recover all of the tetra alkyllead, as much as 6% being retained in the sludge at the completion ofthe distillation.

An object of the present invention is to improve the process ofproducing tetra alkyl lead after.

These objects are accomplished by the following invention whichcomprises treating the alkyl lead sludge with a compound whichefliciently and completely prevents the agglomeration of the lead inthe'sludge, distilling off the major portion of the tetra alkyl lead,then adding a wetting agent to the residue in the still, and thencontinuing the distillation until substantially all of the tetra alkyllead is recovered.

We have found that when engine oil and thiocarbanilide are both added tothe diluted reaction mass and the resulting mass subjected to steamdistillation, the metallic lead forms coarsely granular particles whichdo not agglomerate. These lead particles are of such a size that theycan be readily washed in a stream of water to remove sodium chloride andlike impurities without washing away any of the particles. The washwater will readily drain from the resulting mass of lead particles andsuch mass may be readily dried. Neither engine oil nor thiocarbanilidenor any of the other dispersing agents heretofore employed, when usedalone, can produce such results.

Certain othei substances such as sodium chromate or dichromate, sodiumthiosulfate, sodium silicates and their corresponding water solublesalts of other cations, may be employed in place of the engine oil andthiocarbanilide but without obtaining all of the advantageous featuresthereof.

The above dispersing agents have the disadvantage, common to all theprior dispersing agents, of failing to permit complete removal of thetetra alkyl lead compounds from the sludge, as the metallic leadparticles retain substantial proportions of the tetra alkyl leadcompound, up to 6% of the tetra alkyl lead formed in the reaction.However, we have found that,- by subjecting a lead sludge so produced toa distillation with steam until-the major portion of the tetra alkyllead has been removed or until no further tetra alkyl lead appears inthe distillate, then adding a wetting agent to the sludge remaining inthe still and then continuing the distillation,

substantially all of the tetra alkyl lead may be recovered.

The wetting agents, which we propose to employ, include those substanceswhich lower the surface tension of water, thereby increasing itstendencyto wet metallic lead. The wetting agents, which we have found to beparticularly desirable, are sulfonated castor oils known as Turkey redoil and monopole oil and other sulfonated natural oils. Other wettingagents, which may be employed but which are less desirable because ofcertain problems attendant upon the use thereof, include .thasalts ofalkyl naphthalene sulfonic acids; the condensation products of naphtholsulfonic acids and formaldehyde; the reaction products of oleic acid andthe aliphatic diamines; the higher fatty and unsaturated acids and theirsoaps including both the inorganic cations, such as sodium andpotassium' stearates, and the organic soaps, such as triethanolaminestearate and oleate; the reslnates; and certain commercial products.

In order to more clearly disclose our invention and to illustrate thepreferred method of carrying the same into effect, the followingexamples are given:

Example 1'.-Ethyl chloride is caused to react with a lead sodium alloyin an autoclave. After the reaction is complete, any pressure in theautoclave is released and the sludge is drowned in water to which hasbeenadded thiocarbanilide equal in weight to from 0.01 to 5% of thetotal weight of the lead in the charge and engine oil equal in weight tofrom 0.01 to 5% of the total weight of the lead in the charge. The tetraethyl lead is then removed by steam distillation from the agitated mass.

Example 2.-The process, as disclosed in Example 1, is employed and thedistillation is continued for some time, e. g. 90 minutes, at which timethe distillation appears to be substantially complete as substantiallyno further tetra ethyl lead passes ofi into the distillate. At the endof this time, from 0.01 to 5% of Turkey red oil is added .to the stilland the distillation with steam continued. Within a short time,substantially all of the tetra ethyl lead is removed from the leadsludge.

- In the above description, we have specifically disclosed the use offrom about 0.01 to 5% of each of the agents. However, we-have found thatfrom about 0.1 to 1% thereof is preferred, under ordinary conditions. Bythe use of the wetting agent as described in Example 2, the recovery ofthe tetra ethyl lead is increased from about 1 to 6%.

While we have disclosed certain specific processes employing certainagents inspecific proportions, it will be apparent to those skilled inthe art that many changes and Variations'may be made therein withoutdeparting from the spirit of our invention. Accordingly, the scope ofour invention 'is to'be limited solely by the appended claims construedas broadly as is permissible in view oi the prior art.

-We claim:

'1. The method of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding engine oil andthiocarbanilide to the lead sludge and then distilling oil? the tetraalkyl lead.

2. The method of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding to the lead sludge from about0.01 to 5% of engine oil and about 0.01 to 5% of thiocarbanilide andthen distilling ofl the tetra alkyl lead. g

3. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding a dispersing agent to thelead sludge, distilling off the major portion of the tetra alkyl lead,then adding a wetting agent to the undistilled sludge, and thencontinuing the distillation.

) sludge, distilling oif tetra alkyl lead until substantially no tetraalkyl lead appears in the distillate, then adding a wetting agent to theundistilled lead sludge, and then continuing the distillation.

5. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding a dispersing agent to thelead sludge, distilling off a major portion of the tetra alkyl lead,then adding a sulfonated natural oilto the undistilled sludge, and thencontinuing the distillation. I

6. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding a dispersing agent to thelead sludge, distilling off the major portion of the tetra alkyl lead,then adding a sulfonated castor oil to the undistilled sludge, and thencontinuing the distillation. 7. The process of recovering tetra alkyllead from a lead sludge containing the same which comprises adding adispersing agent to the lead sludge, distilling off a major portion ofthe tetra alkyl lead, then adding a member of the group consisting ofTurkey red oil and monopole oil to the undistilled sludge and thencontinuing the distillation. V a

8. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding to the lead sludge engine oiland thiocarbanilide, distilling off the major portion of the tetra alkyllead, then adding a wetting agent to the undistilled sludge, and thencontinuing the distillation.

9. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding to the lead sludge engine oiland thiocarbanilide, distilling ofi the major portion of the tetra alkyllead, then adding a sulionated natural oil to the undistilled sludge,and then continuing the distillation.

10. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprisesadding to the lead sludge engine oiland thiocarbanilide, distilling off the major portion of the tetra alkyllead, then adding a sulfonated castor oil to the undistilled sludge andthen continuing the distillation.

11. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding engine oil andthiocarbanilide to the lead sludge, distilling off the major portion ofthe tetra alkyl lead, then addinga member of the group consisting ofTurkey red oil and monopole oil to the undistilled sludge, and thencontinuing the distillation. I

12. The method of recovering tetra ethyl lead from a lead sludgecontaining the same which comprises adding engine oil andthiocarbanilide to the lead sludge, distilling ofi the tetra ethyl leaduntil substantially no further tetra ethyl lead passes off, then addingvto the undistilled sludge from about 0.01 to 5% of Turkey red oil 'basedon the lead in the sludge, and then continuing the distillation toremove further amounts of tetra ethyl lead.

13. The method of recovering tetra ethyl lead from a lead sludgecontaining the same which comprises adding to thelead sludge from 0.01to 5% of engine oil and from 0.01 to 5% of thiooarbanilide based on theweight of the lead in the sludge, distilling 011 the tetra ethyl leadwith steam until substantially no further tetra ethyl lead passes off,then adding to the undistilled sludge from 0.01 to 5% of Turkey red oilbased .on the lead in the sludge, and then continuing the distillationto remove all of the tetra ethyl lead.

14. The method of manufacturing tetra alkyl "the tetra alkyl lead withsteam, then'adding a wetting agent to the residue, and then distillingoff the rest of the tetra alkyl lead with steam.

15. The method of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding from about 0.01 to about 5%of sodium thiosulphate to the lead sludge and then distilling off thetetra alkyl lead.

16. The process of recovering tetra alkyl lead .irom a lead sludgecontaining-the same which comprises adding sodium thiosuliate to thelead sludge, distilling 'ofi the major portion of the tetra alkyl lead,then adding a wetting agent to the undistilled sludge, and thencontinuing the distillation.

17. The process of recovering tetra alkyl lead from a lead sludgecontaining the same which comprises adding sodium thiosulfate to thelead sludge, distilling off the major portion or the tetra alkyl lead,then adding a sulfonated natural oil to the undistilled sludge, and thencontinuing the distillation.

18. The process of recovering tetra ethyl lead from a lead sludgecontaining the same which comprises adding sodium thiosulfate to thelead sludge, distilling of! the major portion or the tetra ethyl lead,then adding a wetting agent to the undistilled sludge, and thencontinuing the distillation.

19. The process or recovering tetra ethyl lead from a lead sludgecontaining the same which comprises adding sodium thiosuliate to thelead sludge, distilling off the major portion or the tetra ethyl lead,then adding a sultonated natural oil to the undistilled sludge, and thencontinuing the distillation.

' FREDERICK B. DOWNING.

ALFRED E. PARMELEE. CHARLES J. PEDERSEN. JOSEPH L. STECKER.

